Fastening device



Nov. 4, 1947.. J. N. M. HOWELLs 4 FASTENING DEVICE Original Filed Oqt. 21, 1944 2 Shee ts-Sheet 1 Nov. 4, 1947.

J. N. M. HOWELLS FASTENING DEVICE 2 Sheets-Sheet 2 Original Filed Oct. 21, 1944 INVENTOR. L/ v. M. Ho

Patented Nov. 4, 1947 UNITED STATES PATENT OFFICE.

FASTENING DEVICE John N. M. Howells, Kittery Point, Maine Original application October 21, 1944, Serial 'No. 559,772. Divided and this application January 19, 1946,;Serial No. 642,194.

13 Claims.

This invention relates to fastening devices. More particularly the invention pertains to selfretrovert-ing nails. 7

One of the objects of my invention is to provide a strong na-i1, preshaped so as to "be selfretroverti-ng, and adapted to be driven into material in such "preshaped form.

Another object of my invention is to provide a nail of the character described which will retrovert irrespective of the density of the material into which it is driven.

Another obiect of the invention is to provide a preformed hail of the character described which is so -constructed that it may be readily driven into material without the exercise of special skill.

Other objects of this invention will in part "be obvious and in part hereinafter pointed out.

The invention accordingly consists of the features of construction, combinations of elements and arrangements of parts "which will be exemplified in the constructions hereinafter described, and of which the scope of application will he indicated in the claims.

'The instant application is a division of my cope'nd-in'g application for Means for applying fastening devices, filed October 2-1, 1944, as Serial #559,772, and is a'continuation-in-part of my application for Fastening devices and means for applying the emailed April 24, 1'942,-as'Seri'al N 0. 440,342.

In the accompanying drawings, in which are shown various possible embodiments of my invention,

Fig. 1 is a sectional view showing a notched nail embodying my "invention driven through two wooden-boards;

Fig. "2 is a similar view, butwith only the point of the nail inserted and a driving tool therefor inoperative position;

Fig. 3 is a top plan view of the nail and tool shown in Fig. '2';

Fig. '4 is a front levat'ional view or the driving tool;

Fig. 5 is a .view similar toEig. .1, showing a nail embodying a modified form of my invention;

Fig. s he view-siiniiar to Fig. 2 .showing a'niodifled form of tool for driving :a smooth :shank nail embodying my invention;

:Fig. 7 is an enlarged sectional view taken substantially along the line l1=of Ei'gAB Fig. 8 "is a view similar to'Fig. '2 showing still another modified form of tool and'likewise driving a smooth shank nail; "and Figs. '9 and '10 are enlarged sectional views taken substantially along the line 9--9 and I 6'|=i), respectively, of Fig. 8.

Essentially, a nail embodying my invention has a shank which is curved 'for substantially i-ts entire length to such an extent that the direction of travel of the tip of the nail, along the arc of the shank from the head to the tip, has a component directly opposite to the direction of travel of the nail head. The tip of the nail is preferably pointed and the head, as is usual in the art,

may he provided with -a protecting portion which extends laterally beyond the nail shank to expedite pulling the nail out of material.

The nail may 'be smooth or provided with notches, this depending to some extent upon the type of driving tool employed. This tool may he so constructed that it can successively apply to portions of the nail shank about to enter material a force substantiallynormal-to the surface of said material. Another type of tool in which the driving force is applied to the nail head is shown in my copending application tor Machine for driving curved selh-retrover ting nails, Serial No. 483,594, filed April 19, 1943.

Referring now in detail to the drawings and more particularly to Figs. 1 through 3, I have there shown a self-retrove'rting nail in shaped and constructed in accordance 'vnth my invention. Said nail includes a curved shank 12 which is tipped at one end by a driving point M and is provided at the other end with a head 16.

The shank I2 is preformed to a shape which it is desired to have the nail maintain during and after driving the nail home into -material. Such shape is preferably selected to obtain the best holding eiiect with the material or combinations ofmateria'l with which the nail is to be employed. Furthermore, "as stated above, this curvature of the shank is such that the direction of travel of the driving point M, along the curve of the shank from the 'head'to the point, has a component directly opposed *to the direction of travel of the nail head It. With such a construction any force tending to pull apart two pieces held together by' the nail im'beds the nail tip more securely.

The nail 19, shown in Figs. 1 through 3, is adapted to be used in wood and has acircularly segmental contour embracing a large are of hi most 1 so that "the nail may grip the wood extens'ively and held firmly against retraction. When said nail is driven home, its point M will revert ba-c'k almost to the exposed surface *of the top board W.

Pursuant to my invention, the "curved portion of the shank may embrace an arc o f' from at least 90 to about 180. The greater the arc embraced by the shank the greater will be the self-retroverting effect obtained, but the greater also will be the diffioulty in drivin the nail. It will thus be appreciated that it is desirable to have an are substantially greater than 90, but substantially less than l80a range of from about 110 to 160 providing highly satisfactory results. However, it will be understood that all nails having curved shanks covering an are greater than 90 and whose tips during driving of the nail travel in a direction having a component directly opposed to the direction of travel of the nail head fall within the scope of my invention.

The cross-sectional contour of the shank i2 may be of a generally circular outline except where the same, as hereinafter explained, is notched. However, said shank may alternatively assume any other desirable or conventional outline, as for example, oval, rectangular or triangular. Also, the nail may, as shown, be of substantially uniform diameter from head to tip, disregarding notches, with an abrupt taper to form a point, or the nail may be tapered all the way from the head to the point or be tapered to the point from any portion of the shank intermediate the head and point without affecting the essential novelty or operation of the nail.

The head of the nail should be such that it overhangs the shank, at least partially, and to this end the head may be longer than the diameter or" the shank in one dimension. In order to simplify construction of the driving tool, the head of the nail is preferably no greater than the diameter of the shank at right angles to said dimension. Of course, the head in brad type nails embodying my invention may simpl comprise an end of the shank and have no portion projecting laterally beyond the same.

In the form of the invention illustrated in Figs. 1 through 3, I have shown the head it specially proportioned and formed to cooperate with a driving tool 18 hereinafter more fully described. For this specific purpose, said head is longer than the diameter of the shank i2 in the plane in which the nail is curved and shorter than said diameter at right angles to said plane.

The inner surface of the point 14 may be. formed to the same circular curvature as the shank I2, so that it will guide said shank along the desired path through overlying boards W, W.

Since the nail is not deformed during insertion, it will retain its full original strength and will be able to firmly hold the two wooden boards, W, W, together. It will also be appreciated that since the point and shank stay in fixed angular relationship and the shank is a circularly segmental aro, the bore pierced through the wood by the point i4 is never crushed or mutilated by the shank, and the full length of this bore and the entire peripheral area thereof will thus be available to frictionally engage the nail shank.

The diameter and length of the nail in inches may be varied as desired, and the selection of any particular diameter and length will depend upon the use to which the nail is to be put.

Referring now to Figs. 2 through 4, I have there illustrated an apparatus which will give satisfactory results in driving a nail embodying my invention. Said apparatus comprises a driving'tool l8 composed of a metal post 26 having a hardened upper end, The lower end Of the post is undercut at 22 for a purpose which will soon be apparent. Rivets 24 permanently securea gripping member 26 of resilient material,

such as a strip of spring steel, to the lower end of the post. Portions 28 of the gripping member 26 are bent to lie snugly against the sides of the post and offset portions 3E1 at the end of the portions 28 partially overlie and snugly fit against the front of the post. From the offset portions 39, the ends of the member 28 extend away from the post in two substantially parallel walls 32 which are provided with oppositely indented registered arcuate grooves 34 and 3'. of the same general configuration as the nail shank l2. Said grooves 36 and 36, which together provide a passageway P for the nail shank 12, are so arranged relatively to the post 28 that when a nail i0 is introduced into said passageway, the shank of the nail will traverse the undercut 22 of the post.

The passageway P is slightly narrower than the diameter of the smallest shank to be employed with the tool 18, so that when a nail is introduced into said passageway, it will be lightly frictionally gripped between the two walls 32.

The shank 12 of the nail l8 in this form of my invention is provided throughout its length with a plurality of notches 38, each of which has a short step 4% substantially parallel to the radius of curvature of the shank. The face 42 of each notch is approximately perpendicular to its associated step ii), or to the step 40 of the immediately preceding notch in the direction toward the nail point Hi.

The toe id of the post 29 at the bottom of the undercut 22 is hardened and is so disposed relative to the passageway P that when the point M of a nail ii! is pushed sufficiently far through said passageway, said toe M will lie in the foremost notch 38.

If desired, the toe 55 may be so fashioned that its under surface 45 lies flatly on the steps 48 of the notches, and its forward surface i8 lies flat against the faces 42 thereof.

After the nail has been introduced into said passageway and is lightly held by the walls 32, the point I iwill project beyond the bottom of the tool i8. Said point is placed against the material into which the nail is to be driven, the post is vertically disposed, and a hammer blow is applied to its upper end. The driving impulse which is imparted will be transmitted from the toe 4 3 to the first step' lil of the shank l2, causing the nail to move until said step lies flush against the surface of the material. While the post 29 is moving downwardly, it will remain vertical and, depending upon the formation of the toe 4-4, may shift laterally slightly away from the nail shank. The relative angular position of the nail shank and post will, therefore, be altered. But this relative movement is taken up by spring action of the walls 32. The tool If) is now disengaged from the first notch ll and moved to the second notch, this position being shown in Fig. 2. Thereupon, another driving impulse is applied, This procedure is repeated until the step of the last notch lies flush against the surface of the material. The head of the nail may now be directly driven into the wood by the hammer.

In Fig. 5 I have shown a hall 59 embodying a modified form of my invention, the same being so constructed that it' will provide a greater clinching effect thanthe'semi-circulaf nail l0 above described. In said nail 55] the radius of curvature of the shank 52 varies from the head 54 to the point 56, being least adjacent the head and greatest adjacent the point.- Suchconstruction enables the nailto traverse a'greater span.

s Nails of this type are particularly useful with wall board B. Where a preformed nail is driven through such relatively soft material, the inner surface of the need. not have a curvature which matches that of; the shank 5.2, since said ed. na ma be r int ma by a tool; it e sdto d ive a ha ng, e t r a notched orsmooth shank- The tool; 68; includesa metal or re i i havin a ard d p e The lower end of the tool is enlarged to form adrivi fig head is containing a driving clamp it specially constructed to engage and disengage with any portion of the curved nail shank intermediate its two ends so that driving impulses a plied; to the upper end of; the-post will be transd t r t r ueh t the nail sh o force the s m into th a flsW,

, Said driving clamp includestwo driving shoes 16;, E 8 slidably received in horizontal and vertical slots- Gii, 82; provided in. the driving head l2. Gne driving shoe, for example, the left-hand shoe (6-, has a; convexly curved and groovedright-hand edge which negatively matches the external:

configuration of the, underside of the nail shank 62, Said curved edge is adapted to engage about 90 of the transverse contour of said shank. The right-hand shoe 78 has a convexly curved and grooved left-hand edge 85 which negatively matches the external configuration of the upper side of the curved nail shank. This groove also covers about 90 of the transverse contour of said shank so that the two sides or flanks of the shank are left free when the shoes, l6, l8 engage said shank. Each shoe has an inclined cam slot 88, 99 formed therein. These slots extend in a generally upward direction and converge at a slight angle towards each other, the angle shown in Fig. 6 being exaggerated for purposes of illustration.

A pair of hard, tough pins 92, 94 whose opposite ends are secured in the lateral walls of the driving head '72 bridge the horizontal slot 80, each pin being received in one of the shoe slots 83, 90. The diameter of the pins is slightly less than the Width of the slots, this also being exaggerated for purposes of illustration in Figs. 6 and '7. Springs 86, 98 resiliently bias the shoes it, 18 upwardly. This causes the grooved and curved edges 8t, 86 to be urged towards each other.

The pins 92, 9d are so spaced apart that when the springs urge the shoes upwardly as far as they can go, the bottoms of the slots abutting the pins, the distance between the grooved and curved side walls 8 86 will be less than the diameter of the shank of a nail to be driven. Thus, when a nail shank is introduced between the shoes, it will be bound lightly in the driving tool. This binding action, however, is not sufficient to prevent a nail shank from being forced manually, with ease, through the passageway defined by the shoe edges 84, 86.

The head '72 is provided with entrance and exit apertures I90, 32 forming a continuation of the said passageway defined by the shoes and aiding to hold and position the shank of the nail.

When a driving impulse is applied to the upper end of the tool post it, the pins easie -st move dewnwardly relative to the shoes it, 18- which at such. time lightly trictionally engage the nail raidinitial,- relative downward movement, 5 a s very slight, causes. the shoes to firmly grip. the nail shank; whereupon the shoes transsalt th driving impulse. Such impulse will force the point of the nail in the board W or cause said point to travel further through the boards W, The tool is, nowbacked off, that is, grasped by the tool post and pulled back along the shank. Initially, this movement of the tool moves the pins 32, 9d upwardly relative to the shoes iii, 18 which drag along the shank. Such upward movement will relieve the pressure of the shoesagainst; the shank and permit the tool then to be moved readily to a portion of the s i rther iw z the. mate al i w ic t e ai is ns dr n.-

Ihe h d .8; oft e. s of s ch c nfi ur tion that r prej-ectin-g portions will pass; between he ed es.- ii 26 o he; hoe withou nt i due to he art. hat a edges a spac daddit pt the. dr vin ead. has late al y iis posed grooves 5M1 to, freely pass said head. portion When the nail has been driven in to such xte tthet the head leaves. h e it a r u e 5 .1 he. t o-i.- 24 is to on si and the head the nail directly driven into the wood with the hammer.

Figs. 8: and. I have Shown. still another modified; form. or tool its for. driving a nail 69 having a smooth. shank. Said tool includes a metal driving post H0 having a hardened upper end. The lower end: oi the post is provided with an undercut notch l:i-2'similar to the undercut 22 of the tool. 58 shown in Figs. 2-4. A spur I M1 extends into the bottom of said notch. Said spur has a roughly V-shaped transverse (horizontal) configuration (Fig. 10) and is relieved at its back side i I s to provide a sharp V-shaped driving edge Ill. Rivets H8 permanently secure a gripping member I20 of resilient material, such as a strip of strong steel, to the lower end of the post. Portions I22 of the gripping member are bent to lie snugly against the sides of the post. The ends of these portions I22 extend away from the post and are provided with oppositely indented registered arcuate grooves lZd, I26 of the same configuration as the flanks of the nail shank. Said grooves together define a holding passageway for the nail shank 62 leading past the tip of the sharp V-shaped driving edge H7.

When an impact is applied to the top of the post IN), the driving edge Ill will dig into the nail shank and cause the nail to move arcuately into the wood boards W, W until said edgereaches the upper board -W.

It may be mentioned that the edge H7 is able to dig into the nail shank because the resilient arms I22 spread during driving, allowing the nail shank to leave the holding passageway and to lie flush against the notch H2.

After the nail has been driven to such an extent that the edge H4 is close to the board W, the tool is shifted back along the nail to dispose the edge H1 adjacent another portion of the shank closer to the head, and the driving operation is repeated.

The above described tools are fully shown, described and claimed in my copending application, Serial No. 559,772.

It will thus be seen that I have provided nails which achieve the several objects of my invention,

and which are well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiments above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. A nail comprising a head, a tip and an elongated preformed longitudinally curved shank intermediate said tip and said head, the curvature of the shank being such that the direction of travel of said tip along the curve of the shank from the head to the tiphas a component directly opposed to the direction of travel of said head 2. A nail comprising a head, a tip and an elongated preformed longitudinally curved shank intermediate said tip and said head and embracing an arc of from at least 90 to about 180.

3. A nail comprising a head, a tip and an elongated preformed longitudinally curved shank intermediate said tip and said head, the curvature of the shank being such that the direction of travel of said tip along the curve of the shank from the head to the tip has a component directly opposed to the direction of travel of said head and so that the shank covers an arc of greater than 90.

4. A nail comprising a head, a tip and an elongated preformed longitudinally curved shank intermediate said tip and said head, the curvature of the shank being such that the direction of travel of said tip along the curve of the shank from the head to the tip has a component directly opposed to the direction of travel of said head and 8 so that the shank covers an arc of no more than 5. A nail as set forth in claim 4 wherein the curvature of the shank is uniform.

6. A nail as set forth in claim 4 wherein the shank is notched whereby a driving tool may be employed for driving the nail.

'7. A nail as set forth in claim 4 wherein the shank is provided with notches along the outerside of the curve whereby a driving tool may be employed for driving the nail.

8. A nail as set forth in claim 4 wherein the shank is provided with notches at uniform intervals along the outerside of the curve whereby a driving tool may be employed for driving the nail.

9. A nail as set forth in claim 4 wherein a head is provided which is larger than the shank of the nail in one dimension at right angles to said shank and smaller than the shank in another dimension at right angles to said shank and said first dimension.

1'0. A nail as set forth in claim 4 wherein the curvature of the shank varies from the head to the point, being sharpest adjacent the head and flattest adjacent the point.

11. A nail comprising a head, a tip and an elongated preformed longitudinally curved shank intermediate said tip and said head, the curvature of said shank being substantially semi-circular.

12. A nail comprising a head, a tip and an elongated preformed arcuately curved shank intermediate said tip and said head, the curvature of said shank extending longitudinally thereof substantially 180.

13. A nail as set forth in claim 4 wherein the shank is smooth.

JOHN N. M. HOWELLS. 

